Drive-By-Wire Is Here To Stay

My colleague Bill Wong makes some good points in his article, “Electric Cars May Be Simpler, But Will They Be Safer?” But as Electronic Design’s Power and Analog guy and a new Prius owner, I feel compelled to add a few thoughts of my own. They’re along the lines of “Get used to it,” because drive-by-wire is too important to assembly and logistics economies in the global automotive industry to go away.

By way of explanation, Bill’s comments about aircraft, notably the Airbus airliners, and fly-by-wire take me back a few decades to when I was fresh out of school and contributing in a very minor way to a number of C5A flight-control programs at what was then Garrett-AiResearch. That was where I started to pick up on the roots of this technology.

This wasn’t through the C5A, which was hydro-mechanical, but through another engineer, a Swiss named Jean-François Didisheim, who became my primary flight instructor when I got my private pilot’s license. At Garrett, Jean-François was involved in moving the company from its customary clockwork air-data computers to designs that would be more space-age. (When we first met, he was trying to emulate the functionality of a Systron-Donner analog computer on a digital machine, an IBM 1130 running GOTRAN, if memory serves.)

When contracts got tight in the aerospace industry in 1969, and Jean-François’ project was cut back, he moved his talents to John Conroy’s Aero Spacelines International in Santa Barbara. Aero Spacelines is best known for a series of conversions of obsolete transport aircraft into bulbous supercarriers with various “guppy” monikers, after Conroy’s original “Pregnant Guppy” Boeing Stratocruiser conversion. (For more, see http://en.wikipedia.org/wiki/Aero_Spacelines_Pregnant_Guppy.)

The guppy fleet made money for Conroy by ferrying NASA rocket assemblies from hither to yon, but that wasn’t what Jean-François was involved with. Those were the days of the great supersonic transport (SST) competition between the U.S. (Boeing’s 2707), the Soviet Union (Tupolev-144), and the French/British Aerospatiale-BAC consortium (Concorde). Conroy’s role was to work with Boeing on a flying flight-simulator for Boeing. Jean-François was involved in that project, which is how I know about it.

The point of the Conroy exercise was that while it was possible to simulate the supersonic flight regime of a globe-girdling flight, the approach and landing regimes needed a real flying platform for simulation and for pilot training. Conroy built another modification of an existing transport aircraft, this time with an SST-cockpit mockup, including gauges that read out in Mach numbers, just like the potential future SST. Jean-François’ part was fly-by-wire controls that would make the flying simulator feel like an SST to the pilots on approach and landing.

As it happened, nobody actually trained in that aircraft. Boeing abandoned the 2707, and the Concorde and Tupolev-144 were the only SSTs that ever flew. Jean-François went home to Switzerland, where he spent the rest of his career involved in cockpit design for Swissair. But Conroy’s approach—make one plane feel like a different plane by controlling its dynamic response to control inputs—eventually came to fruition in the Airbus 300-series planes, which all use fly-by-wire to provide a common “feel” to their pilots. The point of that is to allow airlines to transfer pilots between routes with minimal retraining, regardless of the size of the Airbus plane used on the route. It’s as much a cost-saving value proposition as it is a technological one.

That economic pitch works in the automobile business, too. Car makers are simply a few decades behind. To understand the advantages of drive-by-wire, take power steering. Drive-by-wire permits a car maker to use a single power-steering unit for its entire fleet, regardless of steering geometries and weights. Instead of mechanically tuning the steering response, it’s all done in software. (I’ll concede the objection that flaws in software are harder to spot than voids in a casting, if you’ll concede the economic advantage. I also have to ask: what if the Corvair flaw could have been fixed with a simple software patch? Guess who’d have been the 43rd president.)

The economics of drive-by-wire go beyond inventory management. A few weeks ago, I did a story about a test drive of Ford’s Transit Connect plug-in electric urban delivery van. The Transit Connect is a plug-in electric vehicle (PEV) version of a gas-powered Euro-van that Ford has been importing into North America for several years. One of the points the Ford representative made during the drive was that the whole driving experience of the PEV had been tailored in software to match the driving experience for the gasoline-engined van.

The objective of that was to entice fleet managers to become early adopters of at least a few of the vehicles to start with, because they could be certain that their delivery drivers could transition from one power platform to the other with no fuss. That’s the same concept that Airbus uses to sell fleets of jetliners, and the economic driver that supports it goes back many years—to John Conroy and my friend Jean-François.

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